It has been suggested that the normal function of incising, biting, or chewing is controlled or monitored by sensory receptors within the periodontium, specialized nerve fibers in and around the temporomandibular joints, and by sensory fibers within the muscles of mastication. Although the exact mechanism involved in the regulation of bite force is not known, current research would suggest that the sensory system within the musculature may provide for the major control. The purpose of this study is to begin defining the role of the sensory mechanism within the masseters and temporalis musculature by comparing bite force discrimination abilities of normal subjects with and without disruption (vibratory stimulation) to these muscles. The assessment of bite force discrimination will employ the use of two different specially designed and constructed instruments: a strain gauge scale for assessing static bite force discrimination and a mechanical swing beam scale for assessing dynamic bite force with jaw movement. For both instruments, resistance to the subject's biting force, as exerted on an extension beam, can be controlled by the examiner in 100 gms increments up to a maximum of 11,000 gms. The employment of a vibratory stimulation to the masseters and temporalis musculature will involve the use of a signal generator, amplifier and shaker. A frequency of 160 Hz will be used to maximally disrupt muscle function. To determine subject's ability to discriminate differences in bite force, a modified method of constant stimuli will be used. That is, subjects will be presented with a series of paired resistance settings, one at a time, the first of each pair being the referent and the second being the comparator setting. The subject is required to determine whether the second setting is different from the standard. This procedure is continued until the subject's difference limen of discrimination between two settings is established. Defining the role of the sensory system within these muscles for controlling bite force, in addition to advancing our understanding of basic oral physiology, will also provide a rationale for assessing specific clinical patients, such as those with myofascial pain dysfunction, who exhibit a chronic state of muscle tension.